Tea is classified into six categories: green tea, white tea, yellow tea, blue tea (oolong tea), black tea, and dark tea. This site introduces the various teas that CHAMART has sampled.

Dark tea
Post-fermentation tea
Goishi-cha is produced with a two-stage fermentation. The first fermentation is an aerobic fermentation using mold and the second fermentation is an anaerobic fermentation using lactic acid bacteria.
Production area: Otoyo Town, Kochi Prefecture
Flavor: sour, sharp
How to drink: 1 or 2 pieces of Goishi-cha is boiled with about 1 to 1.5 liters of water in a kettle or pan for 10 minutes.

Production method
1. Branches of tea plants with leaves are plucked from the middle of June until the beginning of August. These are steamed in a large caldron for about 2 hours.

2. After removing the tea leaves from the branches they are put in a chamber and placed on a straw mat for about 1 week. Aerobic fermentation is then carried out by adding mold during the first fermentation. Sometimes, the tea leaves are thrown up into the air by hand to make space between the leaves. This is important because it promotes the fermentation.

3. The leaves are then soaked in a wooden bucket with the broth which was made from steaming the leaves. A lid is put on the tea leaves and place a cement block or stones on the lid for about 2 weeks allowing anaerobic fermentation to be carried out with lactic acid bacteria as the second fermentation.

4. The tea leaves are later removed from the bucket and cut into 3 to 4 cm square pieces using a special knife. These pieces are dried in the sun for 7 consecutive sunny days.

History of Goishi-cha
The origin of Goishi-cha is unknown. Tradition says that Goishi-cha was introduced to the Shikoku Region from the mountainous area of Southeast Asia or Yunnan Province, China.

The origin of name of Goishi-cha
It is said that when laying the cut tea leaves on a straw mat they look like Go-stones (碁石) on a Go-board (碁盤) and thus the tea was named Goishi-cha. Go (碁) is an Asian board game.

Recordable folk cultural property
In 2018, Goishi-cha, Awa bancha, and Ishizuchi-kurocha were designated as “recordable folk cultural properties” for their fermented tea producing technology in the Shikoku Region.

Goishi-cha and sweets using Goishi-cha at Michinoeki Osugi (August 2019)

Reference: 
碁石茶 http://goishicha.jp
大森正司、阿南豊正、伊勢村護、加藤みゆき、滝口明子、中村羊一郎編(2017) 茶の事典 初版第一刷 朝倉書店
文化庁 報道発表 平成30年1月19日 文化審議会答申(重要無形民俗文化財の指定等)
https://www.bunka.go.jp/
https://www.bunka.go.jp/koho_hodo_oshirase/hodohappyo/__icsFiles/afieldfile/2018/01/18/a1400149_01.pdf

*The site does not describe all “Teas of Japan” or all “Teas of the World”. Additionally, each article expresses the writer’s personal experience and feelings.
*The information provided on this site may be updated. If you find any information in this article that is incorrect, new, or incomplete, please contact CHAMART.